Serpentine belt slipping

[Immortality]

A worn out auto tensioner unit can also cause the belt to run off even if the pulley doesn't have any play in it.

 

[ephect]

looking from the side on at the edge of the belt and pulley's should give you a good indication of which outlet is causing it to run of course

 

[harrop.senator]

A worn out auto tensioner unit can also cause the belt to run off even if the pulley doesn't have any play in it.

This was the issue with mine. It was tensioning up cocked and the belt kept riding. Was square without tension but spring mustve gone in was pushing a whole rib or two over the block side of the ps pump.

 

[Lug Nut]

Just another thing I'll add about an old VN v6 could be a similar cause but I had the belt tensioner go, so I replaced it and found my belt slipping off after that. Turned out the pulley wheel was put on the wrong way. Flipped it round and never had an issue after that. I'll be honest I know the ecotec is different but still could be a possibility. The pulley wheel on my old thing had a spacer on 1 side to make sure the belt lined up correctly, put on the wrong way and its 5-8mm off centre.

 

[vladimir-brazil]

Guys, you are great!!!

It was the belt tensioner the issue, as you suggested. I was waiting, till now, for a new belt tensioner to arrive and, after installed, at the same instant everything was solved. Brillant!

I've been testing for a couple of weeks before posting here, and, for sure, everything is fine now.

I've update the link that describes the issue: https://goo.gl/uEExqk.
I added a video with the engine now finally working without "eating belts".

I bought a belt tensioner from a chinese manufacturer (wow! that's because to Brazil the freight is incredibly cheaper). So I'll wait a year or more and then again, post if this belt tensioner is indeed made for last, well built. It "seems" like a very good belt tensioner, but how can I know?

If anyone wants to know, the manufacturer I bought the new belt tensioner from is:
Hangzhou Tongtuo Import & Export Co., Ltd
https://tontuo.m.en.alibaba.com
whatsapp: +86 158 6715 1315

I'll also update this thread at any time if, by any chance, this new belt tensioner suddenly stops working as expected.
But for now it seems to be sturdy, well built, although, of-course, there is "iron" and "iron", not all are the same, hard to know without testing.

A zillion thanks!; and
Great rides for all

 

[Mrgmhvtss304]

VS V6 Serpentine Belt riding forward on belt tensioner pulley

Hi Guys,
I have recently had problems with my Serpentine Belt riding forward on my Belt Tensioner pulley to such a degree that it was partial off it. The belt had slipped off and disintegrated itself once , so I decided to replace the tensioner itself with a new one. Put it all back together and it was exactly the same.
I have read heaps of items on here about similar situations but never any fixes for it. Well I have fixed the problem and will share what it was and how to check if it is the same problem in your situation.
What fixed the problem was replacing the Harmonic Balancer. This was on a VS V6 with 250,00km but would be the same on most of the V6 Ecotec Engines that followed. If you are experiencing a similar problem, here is what to look for.
Looking down at the idler pulley between the Harmonic Balancer and the Air Conditioner pulley ( bottom & right of the harmonic balancer) you should see the belt is running forward slightly on that pulley. You should see the shiny part slightly exposed where the belt was normally running beforehand and is now moved forward slightly. It could be as little as 1 to 2mm, it was in my case. This amount of movement will show up at the tensioner pulley as being around 6 to 8mm out.
The result was the belt was riding that far forward on the tensioner pulley and was trying to be pulled back into line by the grooved power steering pulley. It was that far out that it has a very high chance of coming off and shredding. It happened to me twice and I actually caught it riding on the outer lip of the power steering pulley once about to come off.
In my case I had to also replace the tensioner pulley arm again as well, as the belt had been riding on the outer edge of this pulley for about 6 months after initially replacing it, before I actually found and had the Harmonic Balancer replaced. So when the Harmonic Balancer was replaced and the belt was riding correctly the tensioner was jumping and rattling badly. You could hear it rattling when inside the car.
Now all is well, belt running correctly in line, tensioner quiet, happy days.
Hopefully this will help someone out as it took me ages to find and fix this problem. Remember that the belt riding forward on the tensioner pulley is the symptom and not the cause. The root cause was the Harmonic Balancer even though the Harmonic Balancer appeared fine.

Hi mate I've just found this post and what a absolute legend my vy has thrown 3 belts in the past last one a few days ago but was stumped on how and what was causing it as we did the water pump and the tensioner pulley with brand new items plus brand new pulleys for the others and still my belt was sitting nearly on the edge of my tensioner pulley and slipping off as soon as I hit a puddle them I found this post and now I've finally worked out what was wrong the whole time

 

[ChocolateCharlie]

I was having similar problem with my VX throwing the belt and it was mainly to do with the tensior pulley crapping itself and not running true. The main problem I had was that the cheap arse ebay tensioner that I fitted lasted less than six months before it failed, causing the belt to sit towards the front of the pulley where it would slowly shred itself. So I did what I should have done from the beginning and went and bought a proper pully from the shop and it's been fine since. I also found that there are two different lengths of belt, the longer belt matches with the slightly bigger pulley found on later model cars (I think later model, it happened a couple of years ago).